1. Field of the Invention
The invention relates to a drive unit comprising at least an electric drive motor, actuates a functional element, wherein the functional element comprises a stop position for turning off the electric drive motor during its movement.
The invention finds particular application in motor vehicle door locks, wherein the drive unit is, for example, part of a central locking system. Thus, a motor vehicle door lock can be provided with a central locking system having an electronic control unit. In this case, the locking lever is implemented as a central lever. The usual drive unit function is such that when the locking lever is in a locked position, the impact of the (external) operating lever corresponds to an idle stroke. A suitable explanation is found, for example, in EP 1101890 A2. That disclosure is incorporated herein by reference in its entirety.
2. Brief Description of the Related Art
In electric motor drive units, in particular, a rotary member used as a functional element, e.g., a gear wheel, can be actuated. The functional element is not normally self-restrained, but rather it turns unrestrained around an axis. The functional element can actuate levers that assume latched positions. It is thus possible to link the operation of an electric drive motor with the movement of a functional element. In particular, it is possible that the electric drive motor stops when the self-induced motion of the functional element is no longer possible, for example, because it has reached a predetermined latched position (a so-called block mode).
In such drive units, this mode sometimes leads to an increased load on the drive motor, which can cause additional noise. Due to free play between various parts of a motor vehicle door lock, it is difficult to clearly determine the interactions among the components in their various positions and/or to maintain the positions during operation of the motor vehicle.
On this basis, it is the task of the present invention to solve the prior art problems, at least partially.